PhD Project: Genus Gobiodon and its relationship with complexity in Genus Acropora

In recent decades, the field of habitat complexity research has progressed considerably and has now been applied to a number of different ecosystems, both terrestrial and marine [Kovalenko2012]. A variety of methods have been developed to allow the quantification of complexity, utilising both manual measuring techniques and remote sensing techniques, such as ’structure-from-motion’ (SfM) image capture to develop three dimensional models. Most of the remote sensing techniques are relatively new and unrefined with room for improvement, [Rees2019], therefore the refinement of these techniques would be beneficial to the progression of habitat complexity studies. The complexity of a habitat is known to influence the biodiversity of fish assemblages in a variety of marine habitats [Green1996, Griffiths2003c, White2015]. Despite this, very little is known about how the complexity influences the behaviour and sociality of many fish species. The social organisation of a species is often an important predictor of their survival, foraging efficiency and ability to reproduce successfully [Hing2018].

Coral reefs are one of the most notable habitats that display a wide range of complexity at a variety of scales due to the varying morphologies of the various species of corals that form the base structure of the habitat. These complex three dimensional limestone structures offer living and refuge space for a wide assortment of organisms, such as coral gobies, damselfish and shrimp [Bozec2015, Untersteggaber2014]. Many species of coral reef fish are found in social groups, especially those that are specialised for their habitat [Hing2017]. Individuals that belong to these habitat specialist species are often small bodied and well adapted to living in their discrete patches [Wong2013]. They typically have limited mobility around the reef and require their small patch of reef to supply them with the food, shelter and breeding sites they require [Wong2013]. Therefore, it is possible that their social groups and behaviours may be related to the ecosystem characteristics of the environment they inhabitat, such as size or complexity. Features such as these are hypothesised to be key players in determining social group size and dynamics, influencing the population sizes and viability of species. A relationship between the size of group/group structure (larger group or pairs) and the size of the coral structures they inhabit was identified previously in members of the genus Gobiodon [Hing2018]. Hence, it is important that complexity, being the other defining habitat feature, and its influences are understood before the range of active anthropogenic stressors can reduce complexity significantly.